Many products use durable rubber as an outer layer. For example, tires, and shoe soles.
In the case of shoe soles, many types of shoes, such as athletic and sports shoes, have, in addition to an inner sole, a middle sole (sometimes referred to herein as a “midsole”) and an outer sole (sometimes referred to herein as an “outsole”). Shoe midsoles typically use a rubber or polyurethane material that has cushioning and shock-absorbing characteristics, and that is lightweight. However, rubber or polyurethane material that has cushioning and shock-absorbing characteristics, and that is lightweight is generally not durable. Therefore, an outer sole of hard durable rubber is used to give the shoe better wearability.
In order to make shoes that have both a midsole and an outsole, typically, both soles are formed separately, such as by molding; the outsole is then aligned with the midsole so that the outsole can be fastened with a fastening agent, such as glue, or by sewing, to the midsole.
The process of separate formation of the two soles and the alignment and fastening with a fastening agent process adds to the expense of manufacturing a shoe, in terms of both machinery and human resources. Further, the reliability of the bond between a midsole and an outsole depend on the materials from which the midsole and outer sole are made, and depend on the fastening agent used.
A better shoe sole and a better way of making shoe soles is needed.
Similarly, with tires, an outer layer of hard durable rubber in the form of a tire tread is fastened to an inner layer of more shock-absorbing rubber or other material. Many automobile accidents have resulted from the separation of tire tread from the rest of a tire. A better way to make tires is needed.